Abrasive apparatus



March 1, 1966 A. BLOCK ABRASIVE APPARATUS 4 Sheets-Sheet 1 Filed July25, 1962 March 1, 1966 A. BLOCK 3,237,348

ABRASIVE APPARATUS Filed July 25, 1962 4 Sheets-Sheet 2 Ma/er I I `94 90il 25 y 1.512 l/l 55 i? 175 1% VWA/rond March 1, 1966 A, BLOCK 3,237,348

ABRASIVE APPARATUS 4 Sheets-Sheet 5 Filed July 25, 1962 i? 256M/ZMSMarch l, 1966 A. BLOCK ABRASIVE APPARATUS Filed July 25, 1962 4Sheets-Sheet 4 United States Patent O 3,237,348 ABRASIVE APPARATUS AleckBlock, Los Angeles, Calif., assignor to Merit Products, Inc., LosAngeles, Calif., a corporation of California Filed July 25, 1962, Ser.No. 212,430 20 Claims. (Cl. 51--74) This invention relates to anapparatus for abrasively treating the surfaces of a series of vehiclebodies such as automobile bodies as they progress along an assemblyline.

In the processing of the surface of an automobile body, it is desirablefor a number of reasons to sand the bare metal before painting. In thefirst, place, a lead constituent of the sheet metal alloy usually comesto the surface in the form -of minute exudations in the course of thesheet-rolling operation and these surface impurities must be removedbecause they prevent adhesion of paint to the metal. In the secondplace, the bare metal has numerous superficial scratches and nicks thatare readily removed by relatively light sanding. In the third placethere are inevitably deeper scratches and dents which must be cor*rected by special treatment prior to the painting operation but the baremetal is so dull that these defects are difficult to detect. Preliminarysanding -of the bare metal polishes the metal to highlight these deeperdefeats for easy detection. Number 80 grit abrasive has been found to behighly satisfactory for this purpose.

After the prime coat is applied a second sanding operation is desirable.In this second operation, the prime coat is wet-sanded in preparationfor the final color coats.

Heretofore both of these sanding operations have been performed by handin a slow and costly manner. The object of the present invention is toprovide an apparatus to carry out the sanding operations mechanicallyand automatically as the automobile bodies are conveyed along theassembly line.

A basic requirement for carrying out this object is the provision forsome kind of abrasive means to conform to the contour of an automobilebody. This requirement involves two problems, first, to provide anabrasive means which will conform to a given cross sectionalconfiguration of complex curvature and secon-d, to provide such anabrasive means that is capable of following changes in cross section asthe automobile body progresses past the abrasive means.

It has been found that lboth of these problems may be solved by using afiaptype abrasive drum having numerous radially extending flexibleabrasive fingers or narrow leaves coated with abrasive particles forprocessing surfaces by both rubbing action and slapping action. Where anautomobile surface is relatively fiat and approximately parallel to theaxis of such an abrasive drum, the abrasive fingers slap flat againstthe surface. A surface that is at substantial spacing from the drum axisis processed solely by the tip portions of the abrasive fingers butcloser surfaces are processed by more extensive portions of the abrasivefingers. Where the automobile surface is inclined laterally at a steepangle relative to the drum axis the abrasive fingers accommodatethemselves to the con figuration by making edgewise impact with theinclined surface.

Such an abrasive drum may be constructed to conform to a complex crosssectional configuration of an automobile by varying the lengths of theabrasive lingers or leaves in accord with the distances from the drumaxis of the portions of the automobile surface that correspond to thefingers. Thus to process a longitudinal portion of an automobile surfacethat is spaced relatively far from the drum axis or is inclined over arange of radial distances,

"ice

the corresponding longitudinal segment of the drum is provided withrelatively long abrasive lingers. The abrasive drum readily follows thelongitudinal contour of an automobile body because with the radialabrasive fingers long enough to reach a surface of maximum distance fromthe drum axis the drum readily yields radially inward to process asurface of minimum distance from the drum ax1s.

A further problem arises in that the slapping action of the flexibleleaves directly against an edge of a sheet metal object abrades the edgetoo severely and in addition causes the abrasive leaves to wearexcessively. Thus if the travel of the periphery of the abrasive drum incontact with an automobile body is contrary to the direction ofconveyance `of the body, the drum adversely affects the leading edges ofthe sheet metal and, on the other hand, if the direction of rotation ofthe drum is in the same direction as the travel of the automobile body,the drum adversely affects the trailing edges. This problem of what maybe termed edge-on abrasion is met in the present invention by retractingthe abrasive drum to an ineffective position when such a vulnerable edgereaches the drum. Thus, where the sides of an automobile body are cutaway for the wheels, leading and trailing sheet metal edges are exposedand the abrasive drum is retracted in the region of whichever of thesetwo edges is vulnerable by virtue of the direction of rotation of theabrasive drum.

The top of a passenger automobile Ibody also has leading and trailingsheet metal edges, the leading edge being at the forward window Iopeningin which the windshield is to be mounted and the trailing edge being atthe rear opening where the rear window is to be installed. An overheadabrasive drum for processing the upper surface of an automobile bodymust be retractible to an uppermost idle position clearing the lcar topsand must be movable between a first operating position for processingthe car tops and a second lower position for processing the rear decksor trunk portions of the car. The movement of the overhead abrasive druminto its two operating positions must be timed and controlled to avoidslapping action against leading edges for reasons heretofore discussed.

An abrasive drum at the side of the assembly line in alignment with thewheel openings of the successive automobile `bodies must also extend andretract. ln this instance the retraction is to avoid excessive abrasionat either a leading edge or a trailing edge of the wheel openingaccording to the direction of rotation of the abrasive drum.

For `complete automation in the operation of such extensible andretractible drums, some type of detecting means must be provided tosense the passing surfaces of the successive automobile bodies forsynchronized extension and retraction of the drums. Certain diflicultiesarise, however, if an attempt is made to place such a sensing means inthe same region as the drum that it controls. The invention teaches thatthese difficulties may be avoided by placing the sensing means inadvance of the corresponding abrasive drum and by providing anadjustable timer to delay the response of the abrasive drum to thesensing means, With the automobile body traveling at a constant speedalong the assembly line, it is a simple matter to adjust the timer tosynchronize the advance and retraction of the associated abrasive drumwith the movement of the bodies. An overriding manual control isavailable for use when necessary.

The invention also teaches that in processing the side surfaces of theautomobile bodies, advantage may be taken of the fact that the two sidesof an automobile body are symmetrical. The side surfaces are processedat two different stations spaced longitudinally along the assembly line.At one station the right hand side of a car body is sanded under thecontrol of sensing means that contacts the left hand side of the carbody. At the second station the arrangement is reversed, the left handside of the car being sanded under the control of sensing means tha-tcontacts the right hand side of the car. In addition, the inventionteaches that the overhead abrasive drum which processes the uppersurfaces of the car may be controlled by a pair of sensing means, onecontacting the top surface of the car, the other contacting a sidesurface of the car just below the level of the hood.

A further problem arises in that in the operation of a flap-typeabrasive drum for this purpose, it has been found that the abrasiveparticles become worn and dislodged at the tip portions of the flexiblefingers where the slapping action occurs. For this reason, a flap-typeabrasive drum loses efficiency after a period of use, because bare flaptips instead of abrasively coated flap tips act on a surface that isunder process. Efficiency may be restored by severing the worn tips ofthe abrasive fingers to expose fresh abrasive in the outer end regionsof the fingers where the slapping action occurs, but, unfortunately, itis not feasible to ltake time out frequently for this purpose on anassembly line.

The invention meets this last problem by providing for automaticprogressive disintegration of the tips of the leaves of the abrasivedrum as the tips progressively lose their effectiveness. Usually aflap-type abrasive drum with fabric leaves is employed in which the warpof the fabric extends longitudinally of the leaves, i.e. radially of thedrum. An important feature of the present invention is the discoverythat if the warp is oriented laterally of the leaves, i.e. parallel withthe drum axis, the warp threads fall away successively at the tips ofthe leaves as the abrasive becomes exhausted. The adhesive material thatbonds the abrasive particles to the fabric also bonds together thethreads of the fabric, but when the abrasive particles disappear at thetip portions of the leaves to expose the adhesive, the adhesive is soondisrupted to permit the exposed fabric to unravel. The heavy transversewarp threads fall away in succession and the corresponding tip portionsof the weft threads soon disintegrate so that the slapping action iscontinuously shifted radially inward to fresh abrasive tip areas of theleaves.

The invention further provides compensation for the progressiveshortening of the abrasive leaves and the consequent reduction in theeffective radius of the abrasive drum. For this purpose means isprovided to shift the axis of the abrasive drum periodically towards thepassing automobile bodies as required. For those drums that extend andretract automatically, the range of extension and retraction is shiftedto compensate for the progressive shortening of the abrasive leaves.

The features and advantages of the invention may be understood from thefollowing detailed description and the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative FIG. 1is a perspective view of an automobile body on an assembly line passinga processing station where a selected embodiment of the invention is inoperation;

FIG. 2 is a fragmentary horizontal sectional view along the line 2-2 ofFIG. 1 showing a retractible drum that functions on the level of thewheel opening in the side of an automobile body;

FIG. 3 is a fragmentary side elevational view of an overhead abrasivedrum and associated control mechanism for processing the upper surfacesof the automobile bodies, the abrasive drum being shown in position forabrading the surface of the car top;

FIG. 4 is a similar view with the abrasive drum lowered to process oneof the fore and aft decks of the car;

FIG. 5 is a wiring diagram of a control system to cause an abrasive drumto extend and retract automatically in response to a sensing means;

FIG. 6 is a fragmentary end elevation of an automobile body at theprocessing station;

FIG. 7 is a side elevation of the overhead abrasive drum that isemployed to process the upper surfaces of the car;

FIG. 8 is a transverse sectional view of the overhead drum taken asindicated by the line 8 8 of FIG. 7;

FIG. 9 is a fragmentary perspective view showing the manner in which adisposable assembly of the abrasive fabric flaps is fabricated for usereplaceably on the drum shown in FIGS. 7 and 8;

FIG. l0 is a fragmentary plan view of the completed assembly of abrasiveaps;

FIG. ll is a plan view of a fragment of the back of a fabric abrasiveflap of the conventional type with the warp extending longitudinally ofthe flap;

FIG. 12 is a similar view of the back of an abrasive flap of fabricfabricated in accord with the present invention with the warp extendingtransversely of the ilap;

FIG. 13 is a greatly enlarged cross section along the line 13--13 ofFIG. 12 showing how the fabric abrasive flap of the present inventionprogressively disintegrates at its tip by releasing successive warpthreads;

FIG. 14 is a fragmenta-ry perspective View showing how an abrasive drumnormally rotating on a xed axis may be constructed for periodic manualadjustment to compensate for the progressive shortening of the abrasiveflaps of the drum;

FIG. 15 is a wiring diagram of an automatic control system for theoverhead abrasive drum;

FIG. 16 is a series of four diagrams showing how a car body progressespast two sensing means comprising normally open switches shown in thewiring diagram in FIG. 15;

FIG. 17 is a diagrammatic plan view showing how abrasive drums on oneside of a conveyor line may be controlled by sensing means on the otherside of the conveyor line;

FIG. 18 isa diagrammatic fragmentary elevational view showing how aflap-type abrasive drum may be made in segments to process a laterallycurved surface such as the shoulder of an automobile top; and

FIG. 19 is a similar view showing how a flap-type abrasive drum may beconstructed in segments to follow a surface having a more complex curvedprofile.

General arrangement As shown in FIG. 1, successive automobile bodieswithout fenders and windshields and with the hoods and front fendersmissing are moved along a conveyor line at a constant rate by means of apair of conveyor chains 20 and cooperating conveyor rails 21. The uppersurfaces of each of the automobile bodies that are to be abrasivelyprocessed include the surface of the usual top portion 22 of the bodyand, at a lower level, the surface of the rear deck or trunk portion 23.The top portion 22 of the automobile body has a leading edge 24, i.e. anedge that is forward with respect to the direction of conveyance of thebody and has a second trailing edge 25. The rear deck portion 23 has aleading edge 26.

The surfaces of the top portion 22 and the deck portion 23 may beabrasively processed by a single transverse overhead abrasive drum,generally designated 27, which 1s of the flap type. The overhead drum 27is carried by a pair of arms 28 that are swung in unison to move theabrasive drum between a first upper operatingposition shown in solidlines in FIGS. 1 and 3 for processing the top portions 22 of the bodiesand a second lower operating position shown in FIG. 4 for processing thetrunk portions or rear decks 23. The two arms 28 are operated insynchronism by a pair of corresponding power cylinders 29. y

The overhead abrasive drum 27 is mounted on the two overhead arms 28 bypivoted bell cranks 30 which may be rocked by corresponding powercylinders 31 to lift the abrasive drum to an upper idle position that isshown in dotted lines in FIG. 3. The power cylinders 29 that control theoverhead arms 28 and the power cylinders 31 for controlling the bellcranks 30 are controlled by two suitable sensing means 32 and 33 bestshown in FIGS. 3 and 4. The sensing means 32 is an overhead feelerpositioned in advance of the overhead abrasive drum 27, the feelerfunctioning as a normally open switch and being flexed upward by contactwith the top portions 22 -of the successive automobile bodies. Thesecond sensin-g means 33 is a lower feeler positioned on one side of theconveyor line and functions as a normally open switch for operation bycontact with the side of each automobile body at a level just below thetop of the rear trunk portion 23.

The side surfaces on each side of each car body include an upperinwardly inclined curved side surface 35 in the region of the tops ofthe fenders. Below the side surface 35 is a nearly vertical side surface36 and below t-he nearly vertical side surface is a lower outwardlyinclined side surface 38 which is interrupted by a wheel opening 40. Therear edge 42 of the wheel opening 40 is what may be termed a leadingedge since it faces in the direction of conveyor movement. For the samereason the forwardly facing edge 43 at the front end of the car is whatmay be termed a leading edge. On the other hand, the forward edge 44 ofthe wheel opening is a tra-iling edge.

On each side of the conveyor path, an inwardly inclined flap-type drum45 processes the upper side surfaces 35 of the successive cars, asubstantially vertical abrasive drum 46 processes the side surfaces 36of the successive cars and a lower outwardly inclined abrasive drum 48of the same type processes the lower side surfaces 38.

Preferably all of the seven abrasive drums rotate counter to thedirection of conveyance of the automobile bodies, i.e. their peripheralportions in contact wit-h the successive automobile bodies travelrearwardly with respect to the direction of movement of the bodies. Asheretofore explained, when a flap-type abrasive drum tr'averses a sheetmetal object longitudinally thereof from end to end, the drum has anunduly severe abrasive effect on either the leading edge or the trailingedge of the sheet metal object depending upon the direction of rotationof the drum. In this instance since all of the drums rotate counter tothe direction of conveyance of the automobile bodies, it is the leadingedges that are vulnerable.

In the absence of an automobile body at the processing station, asinFIGS. l6-A, the overhead feeler 32 and the lower side feeler 33 areunrestrained and therefore the overhead abrasive drum 27 is at itsuppermost idle position shown in dotted lines in FIG. 3. The overheaddrum stays at its uppermost idle position if only the upper feeler 32 isactuated as in FIGS. 16-B. When an automobile body reaches the positionat the processing station indicated in FIGS. 16-C so that both theoverhead feeler 32 and the lower side feeler 33 are deflected, the

overhead abrasive drum 27 drops from its idle position to its firstupper operating position shown in solid lines in FIGS. l and 3 forprocessing the top of the car. The lowering `of the drum to itseffective position is delayed, however, to avoid excessive abrasion ofthe leading edge 24 of the top portion. When the automobile bodyadvances to the point indicated in FIG. 16-D to release the overheadfeeler 32 while still deflecting the lower side feeler 33, the overheadabrasive drum 27 is lowered automatically to its lower operatingposition shown in solid lines in FIG. 4 for processing the upper surfaceof the trunk portion 23. Here again, however, the downward movement ofthe abrasive drum is delayed to avoid excessive abrasion of the leadingedge 26 of the rear deck 23. As the car lbody subsequently leaves theprocessing station, the lower feeler 33 is released to cause theoverhead abrasive drum 27 to return to its normal uppermost idleposition.

To prevent excessive abrasion of the' leading edges 42 and 43 associatedwith the lower side surfaces 38 of the lautomobile bodies, the lowerabrasive drum 48 is movable between a retracted position away from thepath of conveyance of the automobile bodies and an advanced position forabrasive contact with the bodies. In the construction shown in FIG. 1the lower abrasive drum 48 is extended and retracted by means of a powercylinder 50 under the control of a sensing means or feeler 52 which is anormally open switch responsive to contact with the sheet metal edges ofthe car bodies.

In the absence of an automobile body at the processing station, thelower abrasive drum 48 is retracted from the path of conveyance. Whenthe leading edge 43 of an approaching automobile body deffects thefeeler 52, the lower abrasive drum 48 responds by swinging to itsadvanced or effective position to process the lower outwardly inclinedside surface 38 of the automobile body. When the trailing edge 44 of thewheel opening 40 reaches the feeler 52 to release the feeler, the lowerabrasive drum 48 responds by retracting laterally away from the car toits ineffective position. When the leading edge 42 of the wheel opening40 again deflects the feeler 52, the lower abrasive drum 48 againresponds to take its effective position and remains in its effectiveposition until the trailing edge 54 of the car body passes to releasethe feeler 52.

It is to be noted that each side feeler 52 is positioned in advance ofthe corresponding lower abrasive drum 48 with respect to the approach ofthe successive automobile bodies. As will be explained, suitable timedelay means is effective to delay the response of the abrasive drums 48to the corresponding feelers 52, the delay period being the period ofthe travel of an automobile body from the region of the feeler to theregion of the abrasive drum.Y

To avoid undesirable excessive abrading action by the lower abrasivedrum 48 on the leading edges 42 and 43 of the successive car bodies, anadditional -delay is provided in the responsiveness of the lowerabrasive drums 48 so that the lower abrasive drums are not advanced totheir effective positions against the car bodies until the leading edgestravel far enough to be immune from the abrading action. Thus theresponse of a lower abrasive drum 48 to the signals from thecorresponding feeler 52 is delayed to compensate for the advancedposition of the feeler relative to the abrasive drum, and isadditionally delayed to permit the leading edges 42 and 43 to travelsomewhat beyond the axis of rotation of the abrasive drum. This delayedaction on the part of the lower abrasive drum 48 may leave a smallmargin adjacent the leading edge 42 and another small margin near theleading edge 43 to be subsequently abraded by hand. It is also to benoted that the delayed action results in the lower abrasive drum 48remaining in its advanced effective position as the two trailing edges44 and 54 of an automobile body move past the abrasive drum but theseedges are not excessively abraded by the drum because the direction ofrotation of the drum is counter to the direction of conveyance of theautomobile body.

Structural details The working parts of the apparatus are supported by aframework which straddles the path of travel of the automobile bodiesalong the conveyor line. The framework on each side of the conveyor lineincludes a rectangular angle iron base, generally designated 55 and apair of posts 56 reinforced by diagonal braces 58, the upper ends of thetwo posts being interconnected by a truss comprising two truss members60 and a chord member 62.

As shown in FIGS. 1 and 7, the overhead abrasive roller 27 has twoopposite relatively short end portions or segments 64 of relativelylarge diameter and a long intermediate portion or segment 65 of lesserdiameter. These three portions provide a brush configuration that fromthe opposite side of the source.

is capable of following the curved upper surface of the top portion 22of an automobile body as well as the curved upper surface of the reardeck portion 23.

The overhead abrasive drum 27 is mounted by suitable bearings on atransverse shaft 66 which is iixedly mounted on the ends of thepreviously mentioned bell cranks 30. The two main arms 28 that carry thebell cranks 30 are pivotally mounted on corresponding spindles to swingbetween upper positions for placing the abrasive drum 27 at a level toprocess the automobile top portions 22 and lower positions to place theabrasive drum at a level for processing the surface of the rear deckportions 23 of the automobile bodies. For actuation of the overheadabrasive drum 27, a motor 72 drives a pulley 74 on one of the spindles 70 and the pulley is connected by a belt 75 to a dual pulley '76 on thepivot of one of the bell cranks 30. The dual pulley 76 is connected by abelt 78 with a pulley 80 on the end of the abrasive drum.

The two power cylinders 29, which may be actuated by compressed air, areconnected by hoses with a four-way solenoid valve 86 in a suitablehousing, the valve being operable in opposite respects to cause oppositeoperations of the power cylinders. Each power cylinder 29 is mounted bypivotal means on the corresponding chord member 62 of the framestructure and a piston rod 88 extending from the power cylinder ispivotally connected to the corresponding overhead arm 28. The four-waysolenoid valve 86 is biased to take one of its limit posi-` tions whenit is de-energized, the four-way solenoid taking its opposite positionwhen energized.

In the same manner the two power cylinders 31 that control the bellcranks 30 are connected by hoses 90 With a four-way solenoid valve 92which is operable in opposite respects to cause opposite operations ofthe power cylinders. Each power cylinder 31 is mounted by pivotal meanson the corresponding overhead arm 28 and a piston rod 94 extending fromthe power cylinder is pivotally connected to the corresponding bellcrank 30. Here again the four-way solenoid valve 92 is of the solenoidtype, the valve being biased to take one of its limit positions when itis de-energized.

As heretofore stated, the two feelers 32 and 33 function as normallyopen switches which close in response to contact with an automobilebody. When the four-way solenoid valve 86 for the two power cylinders 29is de-energized, the two piston rods 88 of the power cylinders areextended to the maximum to hold the two overhead arms 28 at elevatedpositions for processing the top portion 22 of an automobile body, andwhen the four-way solenoid valve 92 for the power cylinders 31 isde-energized the piston rods 94 are at maximum extension to hold'theoverhead abrasive drum 27 in an operating position. It is apparent,then, that the overhead abrasive drum 27 is placed in its uppermost idleposition by de-energization of the four-way solenoid valve 86 andenergization of the four-way valve 92. If the four-way solenoid valve 92is then de-energized the power cylinders 31 will actuate the bell4cranks 30 to lower the overhead abrasive drum 27 to its first operatingposition for processing the top portion 22 of an automobile body. If thefour-way solenoid valve 86 is then energized while the four-way solenoidvalve 92 remains de-energized, the two power cylinders 29 will operateto lower the two overhead arms 28 to place the overhead abrasive drum 27at its lower operating position for sanding the upper surface of thetrunk or rear deck 23 of an automobile body.

FIG. 15 shows a wiring diagram for functionally relating the two feelers32 'and 33 with the two fourway solenoid valves 86 and 92. In thediagram the normally open feeler switch 32 is connected to one lead 95from a suitable source and is connected through the coil of a normallyclosed relay 96 with `a second lead 98 One side of the normally openfeeler switch 33 is connected to the lead .and the other side isconnected by a wire 100 with one side of a normally open ar-m 1012 ofthe relay 96. The relay arm y102 closes against a contact 104- Which isconnected by a wire l105 to a timer 106 that is adjustable by a manuallyoperable knob .108. The second side of the timer 106 is connected to astationary contact 110 of a single-pole double-throw switch having aswitch arm 1112.

When the switch arm 112 is positioned against the contact 110, as shownin FIG. 15 for automatic action, it connects the timer 106 with theVfour-way solenoid valve 86, the second side of the solenoid valve beingconnected to the lead 98. When the switch arm 1'12 is in its alternateposition against a second stationary contact 114, the four-way solenoidvalve 36 is connected to a manual control switch 115, the secon-dside ofthe manual switch being connected to the lead 95 by a wire 116. `Foractuation of the timer 106, one of its sides is connected to the wire1116 and the other side is connected by a wire 118 with the lead 98.

The wire 100 associated with the feeler switch 33 is connected to thelead 98 through the coil of a normally closed relay 120 having an arm122. rIhe relay arm 122 is connected to the lead 95 by a -wire `124 andcooperates with a contact that is connected to one side of a secondtimer 126 that is equipped with an adjustment knob 128. The second sideof the timer 126 is connected to one contact 130 of a single-poledouble-throw switch having a switch arm y132. In FIG. 15 the switch arm132 lies against the contact 130 to connect the timer 126 to one side ofthe Lfour-way solenoid valve 92, the second side of the solenoid valvebeing connected to the lead 98. At its alternate position the switcharm- 132 lies against a second contact 134 to connect the four-waysolenoid valve 92 to a manual control switch 135 which is connected tothe lead 95 -by a wire 136. For actuation of the timer 126 one of itssides is connected to the wire 136 and the other side is connected by awire 138 to the lead 98.

If the feeler switch 33 is open regardless of the position of the feelerswitch 32, as in FIGS. 16-A and 16-B, the overhead abrasive drum 27 isretracted to its upper idle position because the fouraway solenoid valve92 is energized through the normally closed relay arm 122 to retract thepiston rods 94 that operate the bell cranks 30 and [because the four-waysolenoid Valve 86 is de-energized with the power cylinders 29 holdingthe overhead arms 28 at their upper positions.

If both of the feeler switches 32 `and 33 are closed as in FIG. 16-C,the relay arm 122 opens to de-energize the fourwvay solenoid valve 92 tolower the bell cranks 30 to place the overhead abrasive drum 27 in itslirst upper operating position for processing the top portion 22 of anautomobile body, the four-way solenoid valve 86 being cut off by therelay 96 to keep the two overhead arms 28 at their upper positions.

When the =feeler switch 32 opens while the feeler switch 33 remainsclosed as in FIG. 16-D, the de-energization of the relay 96 closes acircuit to the four-way solenoid valve 86 through the feeler switch 33and the timer 106 to cause the two power cylinders 29 to lower the twooverhead arms 28 to place the overhead abrasive drum 27 at its secondlower operating position for processing the surface of the rear deck ortrunk portion 23 of an automobile body. The -fourway solenoid valve 92remains de-energized because the relay i120 remains energized throughthe closed feeler switch 33.

The function of the timer 126 is to delay the operation of the four-waysolenoid valve 92 for lowering the overhead abrasive drum 27 from itsidley position to it-s first upper operating position to avoid excessiveabrasion of the leading edge 24 of the top portion 22 of the automobilebody. The function of the timer .-1016 is to delay the operation of thefour-way solenoid valve 86 to delay the lowering of the overheadabrasive drum 27 Vfrom its rst upper operating position to its secondlower operating position to avoid excessive abrasion of the leading edge26 of the rear deck or trunk `portion 23 of the automobile body. Sincethe conveyor chains 20 are driven at a constant rate, it is a simplematter to adjust the two timers 106 and 1,26 for the precise time delaysthat are required.

If it is desirable at any time to operate the `four-way solenoid valve86 by manual control, the switch arm 112 is shifted to its alternateposition `for control of the fourway solenoid valve by the manual switch1115. yIn like manner the switch arm 132 may .be moved to its alternateposition for control of the four-way solenoid valve 92 by the manualswitch `135. As indicated in FIG. l, the two switches `1'12 and 132 maybe toggle switches on the housings of the respective -fouraway solenoidvalves 86 and 92 and the manual switches i115 and 135 may be normallyopen push button switches on the two housings respectively.

One each side of the assembly line each of the inwardly inclinedabrasive drums 45 i-s mounted on an inwardly inclined shaft 142 that is'journalled in bearings 144. A pulley 145 on the shaft 142 is connectedby a belt 146 with a drive pulley 148 that is actuated by a suitablemotor 150.

On each side of the assembly line each of the vertical abrasive rollers46 is mounted on an upright shaft 152 that is journalled in a pair ofbearings 154. A motor 155 yfor actuating each of the abrasive drums 46actuates a drive pulley `155 which is connected by a belt 157 to adriven pulley 158 on the shaft 152.

Each of the extensible and contractible lower abrasive drums 48 Ion theopposite sides of the assembly line is inclined outwardly in accord withthe inclination of the lower side surfaces 38 of the automobile bodiesand is mounted between the two arms of an inclined yoke 159 that sswingable about an inclined axis on a pair of pivot supports 160. Amotor 161 on the yoke is connected by a belt 163 with a driven pulley164 that is unitary with the abrasive drum 48.

The previously mentioned power cylinder that extends and retracts thedrum 48 is mounted on a pivotal support `165 with a piston rod 166extending from the power cylinder `and pivotally connected to the yoke159.

The opposite ends `of each of the power cylinders 50 are connected by apair of hoses 1'68 to a four-way valve 170 in a suitable housing, thefour-way valve being operable in opposite respects to cause extensionand retraction of the abrasive drum 48. The four-way valve 170 is of thesame solenoid type as the previously described valves 86 and 92 and iscontrolled by the circuit shown in FIG. 5 which includes the previouslymentioned normally open feeler switch 52.

In FIG. 5 one lead 172 from a suitable EMF. source is connected to oneside of the four-way solenoid valve 170 and a second lead 174 from theopposite side of the source is connected to the switch arm of asinglepole, double-throw switch 175. At the position shown in FIG. 5 thearm of the switch 175 cooperates with a fixed contact 176 which isconnected by a wire 178 to one side of the normally open feeler switch52. The second side of the feeler switch 52 is connected to anadjustable timer 180 and the second side of the timer is connected by awire 182 to the second side of the four-way solenoid valve 170. Thetimer is adjustable by means of a knob 184 which traverses an arcuatetiming scale 185. The second fixed contact 186 of the switch 175 isconnected to a normally open manual switch 188 which in turn isconnected to the wire 182 by a wire 190. As indicated in FIG. 1 theswitch 175 may be a toggle switch on the housing of the four-waysolenoid valve 170 and the manual switch 188 may be a normally open pushbutton switch on the side of the housing.

When the toggle switch 175 is in the position shown in FIG. 5, theapparatus set for automatic operation, the

position of the abrasive drurn 48 is determined by the feeler switch 52with a time delay introduced by the timer When the feeler switch 52 isopened, the abrasive drum 48 is retracted laterally from the path ofmovement of the automobile bodies along the conveyor line. When thefeeler switch 52 is closed by contact 0f the feeler with the lower sidesurface 38 of an automobile body, the abrasive drum 48 is shifted to itsextended operating position for processing the side surface 38 but thetimer 186 delays the movement of the abrasive drum to its effectiveposition to compensate for the advanced position of the feeler switch 52and further delays the movement to avoid excessive abrasion of theleading edge 43 of the front end of the car and the leading edge 42 atthe wheel opening 40. Here again it is a simple matter toadjust thetimer 180 for the precise time delay that is required. If it isdesirable at any time to extend or retract the abrasive drum 48 bymanual control, the toggle switch 175 is manipulated to connect the lead174 with the push button switch 18S.

All of the abrasive drums 27, 45, 46 and 48 are preferably of theconstruction shown in FIGS. 7 to 13. FIG. 7 is a side elevation of theoverhead abrasive drum 27 and FIG. 8 is a transverse section of FIG. 7.As shown in FIG. 8 the abrasive drum has a hub structure 192 with acircumferential series of longitudinal peripheral slots 194, each slothaving an enlargement at its inner end which may be of circularcross-sectional configuration as indicated. Each of the peripheral slots194 mounts a disposable abrasive assembly 196 comprising several sheets198 of abrasive cloth which extend for the full length of the drum andhave spaced slits 20@ (FIG. 10) forming radially outward abrasive leavesor flaps 202. As indicated in FIG. 9, each `abrasive assembly may beconstructed by interposing a base member 204 between two stacks of theshe-ets 198 and then driving a series of high carbon steel staples 2115through the margins of the sheets and through the interposed basemember. The base member may be made of sheet metal which is folded onitself and which is looped at the fold to` form an enlargement 206 toiit into the enlargement 195 of a slot 194 of the hub structure.

It is not new to construct replaceable abrasive units in this generalmanner, but heretofore it has been the usual practice to cut the fabricsheets in such manner that the warp threads extend radially of theabrasive drums. Thus in FIG. 1l, which illustrates the usualconstruction, the heavier warp threads 208 extend radially of theabrasive drum, i.e. longitudinally of the abrasive leaves or flaps 202.As heretofore stated, a feature of the present invention illustrated byFIG. l2 is that the wrap threads 29S extend 90 from conventionalpractice, the warp threads extending transversely of the leaves or flaps202 to lie parallel with the axis of rotation of the abrasive drum. FG.13 shows on an enlarged scale and in a somewhat exaggerated manner howthe warp threads 208 and the intersecting weft threads 210 of anabrasive flap 282 are normally bonded together by the adhesive coating212 that bonds abrasive particles to one face of the fabric. As theslapping action of the tips of the flaps erodes the abrasive coatings,the bonding of the transverse warp threads 208 is weakened to permit thewarp threads ot unravel and drop away successively in the mannerindicated in FIG. 13. The end portions of the lighter weft threads 210which are exposed by the departure of the successive warp threadsrapidly wear away. Thus the end portions of the flaps 202 were theslapping abrasive action occurs disintegrate in accord with the rate oferosion of the abrasive coating so that the flaps progressively shortenfor continually presenting slapping end portions that have freshabrasive.

Any suitable provision may be made to compensate for the progressiveshortening of the aps with consequent reduction in the effective radiusof the various abrasive drums. For example, each of the two piston rods88 that connect the power cylinders 25 to the overhead arms 68 forextending and retracting the abrasive overhead drum 27 may be made intwo sections interconnected by an adjustment sleeve 214. The two pistonrod sections are oppositely threaded into the sleeve 214 so that thesleeve may be manually rotated to decrease the effective lengths of thetwo piston rods 83 and thus shift the range of reciprocation of theabrasive drum downward to compensate for the progressive reduction ofthe effective radius of the abrasive drum. In like manner the piston rod166 that is operatively associated with each of the lower abrasive drums4S may be provided with a manually rotatable adjustment sleeve 215.

The normally stationary abrasive drums 45 and 46 may be made adjustablein the same general manner. For example, FIG. 14 shows how an abrasivedrum 46a may be journalled in the two arms of a yoke 216 that is mountedon pivots 2.713. The motor 155g for driving the drum 46a is mo-unted onone of the arms of the yoke and is operatively connected to the abrasivedrum by means of two sheaves 220 and 222 interconnected by a belt 224.

The two arms of the yoke 216 are interconnected by a cross bar 225 andan adjustment bar 226 is pivotally connected at one end to the cross barand is pivotally connected at the other end to xed structure 228. Theadjustment bar 226 is made in two sections which have opposite threadsengaged by a manually rotatable adjustment sleeve 230 havingcorresponding opposite threads. Thus periodic manual rotation of theadjustment sleeve 23) extends the effective length of the adjustment bar226 to shift the abrasive drum 46a towards the conveyor line tocompensate for the progressive reduction in the effective radius of theabrasive drum.

FIG. 17 indicates how the two opposite Sides of the automobile bodiesmay be processed respectively at two different stations along theassembly line with the abrasive drums on one side of the assembly linecontrolled by corresponding feeler means on the opposite side of theassembly line.

At the lirst processing station of the assembly line indicated in FIG.17, three abrasive drums 231, 232 `and 233 are mounted at differentlevels on the left side of the assembly line for movement betweenretracted positions and operative positions under the control of threecorresponding feelers 231:1, 232a, and. 233a, respectively, on the righthand side of the assembly line. The feelers sense the leading andtrailing edges of the sheet metal on the right hand side of the assemblyline and thus are able to control the abrasive drums accurately becausethe two sides of the automobile body are identical. No timer is requiredin the control circuit because the feelers may be adjusted.longitudinally of the conveyor line to cause the abrasive drums to skipthe leading edges of sheet metal that would otherwise be excessivelyabraded.

At the next processing station on the assembly line shown in FIG. 17three abrasive drums 234, 235 and 236 mounted at different levels on theright side of the conveyor Iline are controlled in the same manner bycorresponding feelers 234m, 235g and 236g, respectively, on the leftside of the conveyor line. It is apparent that an overhead abrasive drumor drums may be used at either of the two stations for processing theupper surfaces of the top portions and rear deck portions of the carbodies.

FIG. 18 shows diagrammatically how an overhead abrasive drum 27a may besubstituted for the previously described abrasive drum 27 to process thesurfaces of the top portions of the car. In FIG. 18 two relativelynarrow segments 246 and 248 forming a stepped configuration readilyadapt themselves to the curved shoulder of the car top. The remainingportion 250 of the abrasive drum is of uniform diameter to follow therelatively slight changes in curvature of the centra-l region of the cartop.

FIG. 19 shows how an abrasive drum 252 may be constructed to follow themore complex configuration of a portion of a body 254 which is to besanded. The profile of the body 254 forms a valley 255 with sloping sidewalls 256 and 258. The abrasive drum 252 is of stepped segmentedconfiguration with two segments 260 and 262 of uniform diameter toprocess the body on opposite sides of the valley and with a centralsegment 264 of maximum diameter to process the bottom of the valley. Twosegments 265 and 266 step up the diameter of the sanding drum to processthe sloping side wall 256 of the valley and the two segments 268 and.270 -step up the diameter of the sanding drum to process the' side wall258 of the valley.

My description in specific detail of the selected practices of theinvention will suggest various changes, substitutions and otherdepartures from my disclosure within the spirit and scope of theappended claims.

I claim:

1. In apparatus for polishing the surfaces of successive automobilebodies movable along an assembly line and defined by differentlongitudinal zones, the combination of:

support structure adjacent the assembly line;

a plurality of power driven abrasive drums to process the differentzones longitudinally of said surfaces, each of said drums beingshiftable between a retracted ineffective position and an operatingposition in contact with a different one of said Zones and beingrotatable in a particular direction to polish said body in an individualone of the zones and in the operative position of the drums;

sensing means disposed at a position advanced relative to a particularone of said drums in the direction of movement of the bodies to sensethe movement of the bodies past the sensing means;

actuating means operatively coupled to said drums to shift saidshiftable drums between their two positions, said actuating means beingresponsive to the operation of said sensing means to shift the drums tothe operative position; and

means operatively coupled to said actuating means and to said sensingmeans to delay the response of said actuating means to said. sensingmeans to compensate for the advanced position of the sensing means.

2. An apparatus as set forth in claim 1 wherein each 0 of said drums byvirtue of its particular direction of rotation tend-s to abradeexcessively one of a leading edge and a trailing edge of each of saidbodies in the individual zone engaged. by the brush; and

wherein said delaying means delays the response of said actuating meansto avoid excessive abrasion of said one edge.

3. In apparatus for polishing the surfaces of successive automobilebodies movable along an assembly line and defined by differentlongitudinal zones each having leading and trailing edges, thecombination of:

a power driven Hap-type abrasive drum adjacent a particular o-ne of thedifferent zones in the assembly line to abrade an individual one oflongitudinal zones of each of said bodies, said drum being rotatable ina particular direction to process the particular zone except for thearea adjacent to a particular one of said leading and trailing edges insaid zone;

shifting means operatively coupled to each individual drum for obtaininga shift of the drum between a retracted inoperative position displacedfrom the bodies and an operative position in engagement with the bodies;

means disposed relative to said bodies to sense the arrival of saidleading and trailing edges in the particular zone on each body movablealong the assembly line; and

actuating means operatively coupled to said sensing means and to saidshifting means to obtain a shift of said drum between the retractedineffective position and the operative position for obtaining anabrading .13 of the surface of the individual zone of each body by thedrum, said actuating means being responsive to the operation of saidsensing means to retract said drum when said particular edge in theparticular zone of each body is in position relative to the drum for anabrasion of said one edge by said drum and to dispose the drum at itsoperative position at all other times when said individual zone of eachbody is in the region of said drum. 4. The combination set forth inclaim 3 wherein said drum has radial flexible aps with abrasiveparticles bonded thereto, said flaps being made of woven fabric having awarp and a Woof with the warp of the fabric extending transversely ofthe flaps so that the warp successively unravels from the outer ends ofthe aps and drops from the outer ends of the flaps for progressiveshortening of the flaps as the abrasive particles disappearprogressively from the outer ends of the flaps.

S. For use in apparatus for abrading the surfaces of successiveautomo-bile bodies movable along an assembly line and defined bydifferent longitudinal zones, the combination of support structureadjacent the assembly line; and an abrasive drum mounted on said supportstructure in a position relative to said automobile bodies and rotatableon a particular axis to abrade an individual one of the longitudinalzones of the bodies, said drum having radial flaps with abrasiveparticles bonded thereto, said flaps being made of woven fabric having aWarp and a Woof with the warp of the fabric extending transversely ofthe liaps so that the warp successively unravels and drops from theouter ends of the flaps for progressive shortening of the flaps as theabrasive particles disappear progressively from the outer ends of theflaps, including means operatively coupled to said support structure andto said drum to shift the particular axis of said drum toward theassembly line to compensate for the progressive shortening of saidflaps. 6. In apparatus for abrading the surfaces of successiveautomobile bodies movable along an assembly line and defined bydifferent longitudinal zones and having edges defining said zones, thecombination of:

support structure adjacent the assembly line; an abrasive drum mountedon said support structure in position relative to the bodies movablealong the assembly line to abrade one of the different longitudinalzones of the bodies, said drum having radial aps with abrasive particlesbonded thereto, said flaps being made of woven fabric having la warp anda woof with the warp of the fabric extending transversely of the flaps4so that the warp successively unravels and drops from the outer ends ofthe flaps for Vprogressive shortening of the aps as the abrasiveparticles disappear progressively from the outer ends of the fia-ps;

means operatively coupled to said drum to shift said drum through arange between an operating position engaging said bodies and a retractedposition displaced from said bodies to avoid excessive abrasion ofparticular ones ofthe edges defining the individual longitudinal zone ofthe bodies;

means operatively coupled to said shifting means and responsive to themovement of the bodies along the assembly line to synchr-onize theshifting of said drum between the operating position and the retractedposition in accordance with the movement of the bodies along theassembly line; and

means operatively coupled to said drum to obtain an adjustment in theposition of -said drum on said shifting means toward said assembly lineto compensate for the progressive shortening of said flaps.

7. In apparatus for abrading a plurality of longitudinal zones ofsurfaces on each of successive automobile bodies sequentially movablealong an assembly line having a plurality of longitudinally spacedstations, different ones of the zones having different elevations at theopposite sides of the movable bodies and a lower zone on each side ofeach body having a wheel opening defined by leading and trailing edges,the combination of:

a first plurality of abrasive drums at the different elevations on oneside of the conveyor line to abrade the different longitudinal zones onsaid one side of each of said bodies, said drums including a fir-st drumat a first one of the stations -on the assembly line for the lower zoneon said one side of each body;

a second plurality of abrasive drums at different elevations on theother side of the conveyor line to abrade different longitudinal zoneson said other side of each of said bodies, said last mentioned pluralityincluding a second drum at a sec-ond one of the stations on the assemblyline for abrading the lower zone on said other side of each of saidbodies, the second station being longitudinally spaced from said firststation by a distance greater than the lengths of said bodies;

a first sensing means at said first station, on said one side of theassembly line to sense the arrival of the leading and trailing edges onsaid one side of each body;

first actuating means responsive t-o said first sensing means to retractsaid second drum when a particular one of said leading and trailingedges on said other side of eac-h body is in the region of said seconddr-um;

second sensing means at said second station on said other side of theassembly line to sense the arrival of the leading and trailing edges onsaid other side of each of said bodies; and

second actuating means responsive to said second sensing means toretract said first drum when the particular one of said leading andtrailing edges on said one side of the body is in the region of said rstdrum.

8. A combination as set forth in claim 7 wherein each of said first andsecond sensing means is displaced longitudinally of the assembly linerelative to the particular one of the first and second abrasive drumscontrolled by the sensing means to retract the particular drum when oneof said edges is in the region of the particular drum to avoid excessiveabrasion of said particular one of the leading and trailing edges.

9. A combination as set forth in claim 7 wherein each of said first andsecond drums has radial iiexible flaps with abrasive particles bondedthereto, said flap-s being made of Woven fabric having a warp and a woofwith the warp of the fabric extending transversely of the flaps so thatthe warp successively unravels and drops from the outer ends of theflaps for progressive 4shortening of the flaps as the abrasive particlesdisappear progressively from the outer ends of the flaps.

10. In apparatus for abrading the surfaces of vehicular bodies movablealong a conveyor line, which bodies have top surfaces at an elevatedlevel and have deck surfaces at a lower level, the combination of:

power actuated overhead abrasive drum means;

means mounting said overhead drum means for movement of the drum meansbetween a first upper position for abrading the top surfaces of thebodies and a second lower position for abrading the deck surfaces of thebodies;

sensing means in the path of conveyance of the bodies and disposedrelative to the bodies for sensing the change between the top surfacesand the deck surfaces of the bodies; and

actuating means responsive to said sensing means and operatively coupledto said mounting means to obtain a shift of said drum means by saidmounting means between the first upper position and the second lowerposition, said actuating means being responsive to said sensing means tomaintain the drum means at the upper position when said top surfaces arein the region of the drum means and to shift the l. drum means to thelower position when said deck @surfaces are in the region of the drummeans.

11. In the apparatus set forth in claim 10, the mounting means beingalso -operative to move the drum means to a third position displacedfrom the top and deck surfaces of the bodies, and

means in the path of conveyance of the bodies and operatively coupled tothe mounting means for obtaining a movement of the drum means by themounting means between the first and third positions in synchronism withthe movement of the -bodies along the conveyor line to obtain apolishing of the top surfaces of the bodies by the drum means.

12. In apparatus for polishing the surfaces of vehicular bodies movablealong a conveyor line, which bodies have top surfaces at an elevatedlevel and have deck surfaces at a lower level and have side surfacesdefining the top surfaces and the deck surfaces and extending below thedeck surfaces, the combination of:

power actuated overhead abrasive drum means;

means mounting said overhead drum means for movement of the drum meansbetween a first upper position for abrading the top surfaces of thebodies and a second lower position for abrading the deck surfaces of thebodies and a third position above the first position and displaced fromthe top surfaces of the bodies;

rst sensing means in the path of conveyance yof the top surfaces of thebodies for actuation thereby to detect the presence of the top surfaces;

second sensing means in the path of conveyance of the side surfaces ofthe bodies below said deck surfaces for actuation thereby to detect thepresence of said side surfaces; and

actuating means responsive to said first and second sensing means andoperatively coupled to said mounting means to obtain a movement rof saiddrum means between the first, second and third positions in accordancewith the particular combinations in which the first and second sensingmeans are actuated at successive instants of time during the movement ofthe bodies along the conveyor line.

13. A combination as set forth in claim 12 wherein said sensing means islocated at an advanced position relative to said drum means in thedirection of movement of the bodies along the conveyor line; and

wherein means are included to delay the response `of said actuatingmeans to said first sensing means to compensate for the advancedposition of the first sensing means. 14. A combination as set forth inclaim 12 wherein the top and deck surfaces of the bodies are defined byleading edges and wherein the delay means are provided with a sufficientdelay to delay the response of said actuating means until the movement-of the leading edges of the top and deck surfaces of the bodies passthe drum means to avoid excessive abrasion of the leading edges of saidtop and deck surfaces.

15. In apparatus for polishing the surfaces of vehicular bodies movablealong a conveyor line, which bodies have top surfaces at an elevatedlevel and have deck surfaces at a lower level and have side surfacesdefining the top and deck surfaces and extending Ibelow the decksurfaces, the combination of:

power driven over-head abrasive drum means having a retracted uppermo-stposition displaced from the top and deck surfaces of the bodies, a firstupper operating position below said retracted position for abrading saidtop surfaces and a second lower operating position for abrading the decksurfaces of the bodies;

means operatively coupled to the drum means for obtaining a rotation ofsuch drum means;

13 a first sensing means in the path of conveyance of the bodies anddisposed relative to the top surfaces of the bodies for actuation bysuch top surfaces to detect the presence of the top surfaces;

-a second sensing means in the path of conveyance of the bodies anddisposed relative to the side surfaces of the ybodies for actuation bythe side surfaces of the bodies to detect the presence of said sidesurfaces; and

actuating means responsive to said first and second sensing means andoperatively coupled to the drum means to position the drum means at saiduppermost position when neither lof said sensing means is actuated, toposition the drum means at said first operating position when both ofsaid sensing means :are actuated and to position the drum means at saidsecond lower operating position when only the second sensing means isactuated.

16. A combination as set forth in claim 15 wherein said first sensingmeans is located at an advanced position relative to said drum means;and

wherein means are included to delay the response of said actuating meansto said first sensing means to compensate for the advanced position :ofthe first sensing means.

17. A combination as set forth in claim. 15 wherein means are includedto delay the response of said actuating means to said first and secondsensing means to avoid excessive abrasion of particular edges on theautomobile bodies.

18. In apparatus for polishing the surfaces of vehicular bodies movablealong a conveyor line, which bodies have side surfaces with a leadingedge defining the front of the body and with a trailing edge definingthe rear of the body and with first and second intermediate edgesrespectively defining the front and rear edges of a wheel opening,

power driven abrasive drum means having a retracted position displacedfrom the side surfaces of the bodies and having an operative positionfor providing an engagement between the drum means and the side surfacesof the bodies,

means operatively coupled to the drum means for obtaining a rotation ofsuch drum means in a particular direction, first sensing means in thepath of conveyance of the bodies and disposed relative to the sidesurfaces of the bodies for actuation by such side surfaces to detect thepresence of such side surfaces; and

means responsive to the actuation of the first sensing means andoperatively coupled to the drum means to position the drum means in theoperative position upon the movement past the drum means of the portionof the side surfaces of the bodies between the leading edges of the sidesurfaces and the first intermediate edges of the side surfaces and theportion of the side surfaces of the bodies between the secondintermediate edges of the side surfaces and the trailing edges of theside surfaces and for producing a movement of the drum means to theretracted position in the portion of the side surfaces Abetween thefirst and second intermediate edges of the side surf-aces.

19. The combination set forth in claim 18 wherein the actuating meansare provided with a delay in responding to the sensing means to preventthe drum means from engaging the side surfaces of the bodies atparticular ones of the leading and trailing edges and the first andsecond intermediate edges of the side surfaces in accordance with theparticular direction of rotation of the drum means to avoid excessiveabrasion of such particular edges.

20. The combination set forth in claim 18 wherein the bodies areprovided with top surfaces and with deck surfaces at a position belowthe top surfaces and wherein second sensing means are disposed relativeto the bodies movable -along the conveyor line to sense the top surfacesof the l'DOdies and wherein second drum means are mov- 17 18 ablebetween rst positions displaced from the top sur- References Cited bytheExaminer faces and the deck surfaces of the bodies and are movableUNITED STATES PATENTS to second positions for engaging the top surfacesof the bodies and are movable to third positions for engaging thegbisttr et al deck surfaces lof the bodies and wherein second actuating5 2719388 10/1955 P5 er s 51-74 means are responsive to the first andsecond sensing 2871632 2/1959 Comog "M -337 means to move the seconddrum means between the rst,

2,964,887 12/1960 Orozco 51-389 second and thlrd positlons dur1ng themovements of the 3 023 550 3/1962 Krstok 15 230 12 bodies along theconveyor lines to provide a polishing 3035293 5/1962 Larson 15 '21action by the second drum means on the top surfaces and 10 deck surfacesof the bodies. LESTER M. SWINGLE, Primary Examiner.

1. IN APPARATUS FOR POLISHING THE SURFACES OF SUCCESSIVE AUTOMOBILEBODIES MOVABLE ALONG AN ASSEMBLY LINE AND DEFINED BY DIFFERENTLONGITUDINAL ZONES, THE COMBINATION OF: SUPPORT STRUCTURE ADJACENT THEASSEMBLY LINE; A PLURALITY OF POWER DRIVEN ABRASIVE DRUMS TO PROCESS THEDIFFERENT ZONES LONGITUDINALLY OF SAID SURFACES, EACH OF SAID DRUMSBEING SHIFTABLE BETWEEN A RETRACTED, INEFFECTIVE POSITION AND ANOPERATING POSITION IN CONTACT WITH A DIFFERENT ONE OF SAID ZONES ANDBEING ROTATABLE IN A PARTICULAR DIRECTION TO POLISH SAID BODY IN AINDIVIDUAL ONE OF THE ZONES AND IN THE OPERATIVE POSITION OF THE DRUMS;